Despite the advances in the treatment of pre-B-ALL leukemia in children, adult pre-B-ALL continues to represent a major challenge. This work focuses on the use of differential responses to fasting conditions between normal and cancer cells to achieve cancer-free survival. We show that a fasting-mimicking diet in combination with vincristine causes a synergistic increase in the toxicity to pre-B-ALL cells resulting in high cancer cell death. While fasting is not sufficient to promote cancer-free survival, the combination of fasting/FMD and vincristine promotes autophagy inhibition, which is at the center of the high toxicity phenotype specific to leukemia cells, possibly through a mechanism involving immune cells.